TRANSACTIONS OF SECTION I. 991 
1. The slip is warmed gently with a crystal of iodine, when the yellow iodide 
of lead is formed. 
2. The lead is dissolved off with acetic acid and sulphuretted hydrogen passed 
through the solution. 
The magnesium strips can of course be used repeatedly, after carefully washing 
with acid and distilled water. The method is at bottom an electrolytic one, but 
its simplicity, and so far as our experiments go, its accuracy strongly recommend 
it to clinicians. 
There is no necessity for any special apparatus, and the actual working time 
may be safely put as less than one hour. 
In aqueous solution we have obtained results when lead has been present in 
the proportion of 1 part in 50,000. 
The results have been equally good in urine. Clinically we have found lead 
in the urine of two cases under the care of one of us in the Royal Infirmary, and 
in the vomit from one case. 
